Inside Surface Temperature Research Articles

Exploring Biomaterial-Based CoolRoofs: Empirical Insights into Energy Efficiency and CO2 Emissions Reduction

The Cool Roof concept, known for its efficiency in summer due to high temperatures during this period, employs a light coating that covers the roof to prevent the absorption of heat and maintain lower indoor temperatures. This study integrates a chemical component with biomaterials to enhance performance and reduce CO2 emissions. The composition investigated in this research is recognized for its durability and ability to lower outside temperatures, thereby mitigating the urban heat island effect. This experimental study evaluates the sustainability of CoolRoofs in a cold room located in Signes, France. Temperature measurements are conducted from 25 September 2023 to 27 July 2024, both with and without the coating, to assess energy performance and CO2 emissions. The selection of the building type ensures optimal performance in both summer and winter. Results show that the maximum outside and inside surface temperatures for a Cool Roof are 48.7 °C and 25.6 °C, respectively, compared to 72.9 °C and 32.2 °C for an uncoated roof. Additionally, implementing a CoolRoof reduces thermal load through the cold room by 56%, while CO2 emissions can be reduced by up to 27.31 kg CO2/m2 over a 20-year period. This study presents a solution for enhancing energy and environmental performance year-round using a resilient composite.

Comprehensive analysis of thermal performance and low-grade energy charging efficiency of pipe-embedded building envelopes enhanced with single-level tree-shaped fin structures

Pipe-embedded walls (CnPWs) are structural and energy composite building components that can resist external disturbances by forming stealth thermal shielding layers. To tackle the mismatch between the heat charging rate and heat diffusion rate during energy charging processes, as well as the unsatisfactory robustness of stealth thermal shielding layers, the single-level tree-shaped metal finnd pipe-embedded walls (TfPWs) are proposed. To verify the effectiveness of TfPWs and obtain dynamic performances, a simulation study is conducted on 8 risk variables in 4 pairs through the validated numerical model. Results showed that the improved design was effective in obtaining more robust thermal shielding layers in auxiliary energy supply mode, the effect gained prominence as both the injection temperature and pipe spacing were augmented. In room heat load reduction mode, favorable benefits arise when pipe spacing exceeds 400 mm. The maximum increase rate of total injected energy under different reduction ratios of external insulation layer was 11.83%–31.91 %, while the maximum extra total heat loss was 5.33 %. Secondly, the trunk fins and branch fins played different roles in minimizing the excessive heat accumulation surrounding pipes, and the vertical and horizontal sizes of heat accumulation region mainly increased with the increase in trunk fin size and branch fin size respectively. Meanwhile, the utilization efficiency of fin material was higher when trunk fin size was smaller, and parameter combinations with trunk fin size of 0.2b and branch fin size of 0.4a/0.6a could achieve a better balance between material input and performance increase. Thirdly, the improvement effect of single left branch fin schemes was close to that of double branch fin schemes and significantly better than that of single right branch fin schemes. It was recommended to use single left branch fin schemes with an inclination angle of 60°. Finally, even if the reduction ratio of external insulation layer in different cities increased to 80 %, the inside surface temperature of TfPWs was still greater than room air. Taking CnPWs with standard external insulation layer as references, the TfPWs applied in Harbin, Beijing, and Shanghai could achieve similar or better results even when the reduction ratio of external insulation layer increased to 60 %, while TfPWs applied in Guangzhou could exhibit better performance even when the reduction ratio of external insulation layer increases to 80 %.

An experimental and numerical investigation of the thermal performance of phase change materials in different triple-glazed window configurations

Phase Change Materials (PCM) may be excellent thermal insulation due to their poor conductivity and high heat capacity. Researchers are adding PCM to windows. This integration modifies internal surface temperatures and delays peak temperatures to improve indoor thermal comfort. This work investigates experimentally and numerically the impact of the different filling materials in four Triple Glazed Windows (TGW) configurations in an Iraqi environment: the first window filled two cavities with air (standard); the second window has one cavity filled with a PCM and the other with air; the third window has blinders with various tilt angles in one cavity and PCM in the other cavity; and in the fourth window, both cavities are filled with PCM. Numerically utilizing Computational Fluid Dynamics to evaluate the thermal performance of TGW. In August, when the solar radiation was at its maximum (623 W/m2), the results showed that the peak interior surface temperature dropped by 4.51, 13.28 and 11.53 % in the TGW configurations (PCM-air), (blinder-PCM), and (PCM-PCM), compared to the standard TGW. The fourth window increased the time lag by 2 h, effectively shifting the load and in the third window, the best tilt angle blinder is 45°

Thermal and energy performance assessment of naturally ventilated roofs with phase change material

The effect of incorporating phase change material (PCM) into roofing systems combined with natural ventilation is numerically and experimentally investigated. Four roof configurations, including ventilated and unventilated options with and without an air gap between the PCM and the insulation material, are subjected to experimental research during the winter season in a semi-arid climate using two fully instrumented modules. A sensitivity analysisis conductedthrough annual transient simulations fordifferentair gap dimensions and schedule openings. The experimental campaign demonstrates a decrease in the maximum peak indoor air temperature of between 1.9 and 4.4 %when the PCM is employed. Additionally, an increase in the minimum indoor air temperature between 4.4 and 10.4 % is achieved. Similarly, an improvement in the thermal performance of the PCMis observedwhen natural ventilation occurs, and it positively influences the interiorsurface temperature of the roof.Furthermore, the numerical results show almost zero annual thermal balance in the scenario where natural ventilation is allowed in the combination of 12 and 24 h per day through ducts with a diameter of 15 and 20 cm, respectively. Finally, this demonstrates that PCMroofs enhanced with natural ventilation could be an energy-efficientalternative for semi-arid climates under well-configured ventilation schedules and roof layers.

Hygrothermal Performance of the Hemp Concrete Building Envelope

The search for environmentally friendly and low-carbon-footprint construction materials continues progressively. Researchers are now interested in innovative materials that connect with the principles of sustainable construction, and materials such as hemp concrete prove to be promising. This article presents the results of a study that aimed to evaluate the hygrothermal performance of hemp concrete integrated into the building envelope using the hygrothermal tool WUFI Pro 6.2. The simulation model was compared and verified with existing models before its utilization for this study. The results of this verification were in good agreement, which gave us more confidence in its application for further parametric studies of building envelopes in hot climate zones. Three wall systems were simulated: (i) a wall system with hemp concrete, (ii) a compressed earth block wall, and (iii) a cement block wall. The most important variables used in the simulations were the hygrothermal properties of the materials or wall components and the incident solar radiation. The simulation results showed that hemp concrete has good thermal performance and temperature and humidity regulation capabilities of the building envelope. The interior surface temperatures of the hemp concrete walls were between 22.1 °C and 24.6 °C compared to the compressed earth block and cement block walls, where the surface temperatures were between 22.0 °C and 27 °C and between 21.2 °C and 28.7 °C, respectively, and between 23 °C and 45 °C for the exterior temperatures. These values remain the same with the increase in exterior temperatures for hemp concrete walls. In conclusion, hemp concrete could be a great alternative material for use in construction for hot climate zones.

Wall-embedded micro heat pump for radiant heating in buildings: Evaluation of energy and thermal comfort performance

This paper presents a novel radiant heating system with a wall-embedded micro heat pump (WEMHP) for residential buildings. The interior surface temperature of the exterior wall-section empowered by the micro heat pump is independently controlled, enabling distributed thermal comfort delivery. The micro heat pump consists of a miniature compressor along with an aluminum roll-bond condenser and evaporator. In contrast to conventional hydronic radiant systems and heat pumps with separate indoor and outdoor units (i.e., split systems), the WEMHP is a “packaged” system that would not require on-site installation and charging of a secondary water loop and circulation pump or refrigerant piping. This could ultimately lead to reduced installation and maintenance costs. In this study, a detailed system model is presented and integrated with a single-zone building model to assess the energy performance of the WEMHP in heating mode. For a designed living room scenario with an external wall WEMHP-to-wall ratio (HPWR) of 0.6 and window-to-wall ratio (WWR) of 0.2, the simulation results show that up to 23 % energy savings compared with a baseline air-to-air heat pump are possible. The results also indicate the HPWR needs to be higher than 0.4 to achieve performance comparable to the baseline. Additionally, experiments were conducted in a laboratory environment in which surface temperatures were controlled to emulate different scenarios for integration of WEMHP technology and to evaluate thermal comfort conditions. The experimental results show that the median operative temperature differences in the indoor environment were within 0.5 °C for various locations while the largest radiant asymmetry was 2.2 °C for the designed room configuration. Moreover, simulations were conducted to evaluate thermal comfort conditions in applications having a smaller HPWR of 0.4 with various values of WWR. Overall, the combined simulation and experimental study shows that the WEMHP has potential to reduce energy use while maintaining thermal comfort at acceptable levels where the HPWR is higher than 0.4.

Application of solar energy storage system in building structure design and its thermal process analysis

In order to understand the application and thermal process of solar energy storage system in building structure design, a research on the application and thermal process analysis of solar energy storage system in building structure design is put forward. This paper will take the outdoor climate conditions of residential buildings in a province as an example to conduct thermal analysis on the heat collection components and heat storage components of urban residential buildings. The building under test is a university teacher?s residence located in the university campus of Chengguan District of the city. It is a multi-storey building with a total of five floors, and the building is on the top floor. The experimental results show that the heat storage effect of the thick exterior wall can effectively reduce the temperature fluctuation of the exterior wall. The difference between the maximum and minimum values of the exterior wall surface temperature is 19?C, and the difference between the maximum and minimum values of the interior surface temperature is 5.4?C. The difference between the maximum and minimum temperature of the north exterior wall is 4.9?C, and the difference between the maximum and minimum temperature of the inner surface is 1.6?C. The work of this paper lays a foundation for the quantitative research on the temperature control of building heat collection and storage components, and provides a theoretical basis for solar heat storage.

Numerical investigation of the effects of different influencing factors on thermal performance of naturally ventilated roof

Ventilated roofs can improve thermal performance and reduce the energy consumption of building roofs. In this study, the optimal design parameters and adaptability of naturally ventilated roofs were determined through numerical investigations of the effects of different influencing factors on their thermal performance. A three-field coupling numerical simulation method considering temperature, flow, and solar radiation fields was used to improve simulation accuracy. The research results show that the optimal air gap layer thickness of a naturally ventilated roof increases with increasing roof length, which has not been considered in previous studies. The peak interior surface temperature of the ventilated roof increases with increasing outdoor atmospheric pressure. Ventilated roofs with a 30°–40° slope have a stronger stack effect and can better discharge solar heat gains when compared to roofs with other slopes. Interior surface temperature is reduced when phase change materials is set in the upper rather than the lower roof during summer. Phase change materials should be set in the upper roof to save energy. Small damage holes in the upper roof don't apparently affect the ventilated roof thermal performance. The findings of this study can guide optimization design and help evaluate the energy-saving effects of naturally ventilated roofs.

Characteristics of human-related droplet dynamic patterns inside urban bus with numerical simulation approach: Impacts of solar radiation, ventilation modes and humidity

Nowadays, urban bus has become one of the closely human-related environments. The exhaled droplets when passengers breath, talk, cough and sneeze will undergo a series of significant dynamic process in the enclosed bus. The characteristics of aerosol dynamic process has been demonstrated to be great impact on aerosol transmission and the occupants’ exposure levels, but has not been fully understood yet. This study analyzed the airflow organization and aerosol transmission during actual commuting period inside urban buses by employing the Eulerian-Lagrangian technique and realizable k-ε turbulence model. Three key factors including solar radiation, ventilation modes and humidity were added to reflect the impacts of the abovementioned parameters on aerosol dynamic and transmission patterns. The results showed that solar radiation will lead to a growth of up to 64.4% of bus interior surface temperature in winter. The air conditioning and ventilation inside the bus can meet the thermal comfort needs of passengers. The droplets start to spread in the entire compartment in 30–90 s and almost affects all the passengers, and those sprayed by standing passengers diffuse faster, affecting 8 passengers around the target passenger within 30 s. When relative humidity (RH) = 90%, the residential particle size after evaporation will be 27.9%–38.38% larger than that under RH = 30% with diameter over 15 μm. The findings in the study should be a guidance when accurately forecasting the aerosol dynamic, transmission, exposure levels and smart control for ventilation system inside transport environment.

Thermal characterization of a novel heated glass element

Although the U-value of glazing has improved significantly in the last decades, the thermal transmittance of windows remains relatively high compared to opaque elements of the thermal shell. Consequently, glazing has a relatively low interior surface temperature in the heating season, which can cause thermal discomfort. A novel heated glass element has been developed, allowing for the control of its interior surface temperature. In-situ measurements were conducted on a heated glass element, with the objective to (i) characterize its thermal behaviour, (ii) assess its thermal performance and (iii) to assess its impact on thermal comfort. The examination of heating-up and cooling-down curves of the heated glass element revealed that cooling-down is a slower process (τ2 of 100 – 145 minutes) than heating-up (τ2 of 70-85 minutes). In terms of thermal performance, it is shown that most of the heat provided by the heated glass element is effectively directed towards the room, rather than lost to the outdoor environment. The efficiency depends on the temperature difference between interior glass surface and the room, with efficiencies of 58 – 65% reached at surface temperatures of 23 - 25 °C, and efficiencies of 90% reached at surface temperatures of 39 – 43 °C. Comparative measurements of thermal comfort in a room with the heated glazing, and in a room with conventional triple glazing show an improvement in operative temperature.

Transparent wood with heat shielding and high fire safety properties for energy saving applications

Improving the energy efficiency of buildings is critical to achieving net-zero and addressing the global energy and climate crises. By adopting simple spin-coating, a solar-blocking coating (Cs0.33WO3) was prepared on transparent wood (TW). Meanwhile, a liquid and transparent flame retardant (BPDP) was employed to enhance its fire safety. The chemical composition, physical morphology, the thermal stability, and the fire safety of the resulting heat-shielding TW were analyzed using FTIR, XRD, SEM, TGA, and Cone, respectively. Field tests and simulations were conducted to evaluate the solar-blocking capacity and energy-saving potential of the heat-shielding. The char yield (CY) of heat-shielding TW was increased from 7.3 % to 17.1 % due to the catalytic carbonization effect of BPDP and inorganic coating. The heat-shielding TW demonstrated significant solar-blocking capabilities, with a 46.63 % reduction in solar transmission compared to the original TW. The interior surface temperature (Ts) of the heat-shielding TW model was 10.2 °C lower than that of normal glass, indicating its remarkable heat shielding performance. Energy-saving simulations based on experimental findings revealed that such heat-shielding TW achieved energy savings of 9.6 %, 7.7 %, and 6.2 % in Hong Kong, Shanghai, and Singapore, respectively, when compared to traditional glazing glass. Overall, the prepared heat-shielding TW shows promise as a novel candidate for window applications, offering improved energy efficiency.

Summer thermal and energy performances assessment of a modular hydronic thermal barrier wall for ultra-low energy buildings - A field experimental study

Hydronic thermal barriers with ultra-low carbon emission attributes are progressively gaining prominence in the competition of thermal insulation solutions for opaque envelopes of low-energy buildings due to their excellent thermal performance and low-grade energy utilization potential. This paper introduces a novel approach involving a modular hydronic thermal barrier wall (MHTB) that incorporates preset pipe cavities and replaceable filling material. This proposition seeks to address the challenges confronted by conventional hydronic thermal barrier walls (CHTBs), specifically in terms of internal heat transfer enhancement and rapid assembly/dismantling. On-site thermal performance tests and energy-saving evaluations were conducted in summer conditions based on three scaled-down rooms with MHTB, CHTB and a conventional external insulation wall as the south walls. The results showed that the MHTB could significantly reduce heat passing through the south wall in summer, resulting in a decreased cooling load attributed to the wall and subsequently lowering indoor temperatures. At a charging temperature of 17.0 °C, the MHTB exhibited a reduction of 11.3 °C in interior surface temperature compared to the conventional external insulation wall, accompanied by a corresponding increase of 2.76 kWh·m−2 in cumulative heat flux. In addition, the MHTB could effectively mitigate inhomogeneous heat transfer within the wall, enhancing the overall heat transfer effect. Across the four investigated conditions, the MHTB with a steel grit-sand mixture as the filling material demonstrated an approximate 4.7% increase in cumulative heat flux and a 12.2% enhancement in cumulative cooling quantity compared to the CHTB. Overall, the findings substantiated the efficacy of the MHTB system and offered a crucial point of reference for advancing research in optimizing the performance and modular construction of hydronic thermal barrier walls.

Potential quantification and impact factors analysis of energy flexibility in residential buildings with preheating control strategies

Demand response (DR) is an effective method for achieving energy flexibility. Preheating can store a certain amount of energy in the building while simultaneously reducing the heat load. The energy flexibility of a building during the heating season mainly depends on the types of DR events, the thermal performance of the building envelope, and weather conditions. Analyzing the impact of these factors on the preheating performance and exploring their interactions can reveal the potential for energy flexibility. This study proposes a simulation-based method to evaluate the energy flexibility of a residential building in Kitakyushu, Japan from the perspectives of energy efficiency, load and energy reduction. Rule-based control strategies are applied to heating, ventilation, and air conditioning systems. The results show that compared to preheating temperature of 24 °C, high insulation building at 25 °C achieves energy efficiency improvement of 3.5%–14.8% and load reduction increase of 1.6%–22.2%. Compared to low insulation building, preheating at 25 °C for 1 h increases energy efficiency in high insulation building by 6.2%–10.3%, with corresponding load reduction increase of 1.0%–19.1%. Extending the preheating duration improves load reduction but leads to heat loss. Preheating during heating system startup should be avoided as it produces the worst energy flexibility. Moreover, statistical analysis identifies key indicators for energy reduction: the inside surface temperature of the exterior wall (Pearson correlation coefficient = 0.820, standard regression coefficient = 0.924), followed by global horizontal radiation and building insulation performance.

A comprehensive evaluation of water spray system on transparent roof towards optimal operation schedule

Indoor overheating induced by transparent roofs sharply increases the building energy consumption. Water spray offers a potential solution but requiring effective strategy to balance cooling effects and cost-effectiveness. Aiming at a spray system installed on transparent roof (63.2 × 24.6 m) of a mixed-use building in Guangzhou, China, this study provides a comprehensive evaluation of multiple strategies including continuous and intermittent operation with different spray/interval time. In sunny weather, continuous spray reduces the exterior, interior surface temperature, and long-wave radiation by 17.5 °C, 9.6 °C, and 66.3 W/m2, respectively. Besides, the indoor air temperature, globe temperature, and mean radiant temperature are also lowered by 4.4, 5.2, and 5.7 °C, respectively. Comparatively, the intermittent spray produces worse cooling effect, the reduction of exterior, interior surface temperature, and long-wave radiation are 9.4–15.9 °C, 4.1–7.8 °C, and 24.1–47.7 W/m2, respectively. The intermittent operating conditions, sorted according to the exterior surface temperature reduction, are ranked as 30/10 > 20/10 > 10/10 > 10/50 > 10/20 min, with the cooling effect not decreasing linearly with interval time, but increasing monotonically with spray time. The air conditioning electricity saved by continuous spray is higher than that by intermittent spray, but the water pump electricity and water consumptions are higher as well. Technical-economy evaluation indicates that water consumption is primary cost factor in spray systems and intermittent spray with 10/50 min is the optimal scenario. This study provides insights into the economical and efficient operation of transparent roof spray system, and lays a foundation for its smart control.

Investigation on properties of phase change foamed concrete mixed with lauric acid-hexadecanol/fumed silica shape-stabilized composite phase change material

This experimental study developed a phase change foamed concrete (PCFC) with suitable temperature regulation and heat storage capabilities utilizing experimental design and numerical simulation. With the porous material adsorption method, a shape-stabilized composite phase change material (PCM) was prepared using fumed silica to absorb Lauric acid-Hexadecanol (LA-HD) binary eutectic. Through the Differential Scanning Calorimetry (DSC), Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectrometer (FT-IR), Thermal Gravimetric Analyzer (TGA) and liquid leakage tests, the results indicate that the best mass ratio of LA to HD in LA-HD binary eutectic is 53:47. The maximum adsorption ratio of fumed silica for LA-HD is 60 % (wt). The adsorption process is only a physical combination without chemical reaction, and the proposed composite PCM has stable morphological structures and physical properties. The effect of composite PCM on the dry density, compressive strength and thermal properties of PCFC was explored by changing the content (5 %, 10 %, 15 %, 20 %, 25 %, 30 %) of composite PCM in PCFC. The finite element software ABAQUS was used to establish the model of the PCFC wall, and its heat storage and temperature regulating performance was studied. The experiment results show that the dry density, compressive strength and thermal conductivity of the PCFC gradually decrease with the increase of composite PCM. When the content of composite PCM is 30 %, the dry density, compressive strength and thermal conductivity reach the minimum values of 579.6 kg/m3, 1.192 MPa and 0.105 W/(m·K), respectively. With the increase of composite PCM, the phase change temperature, latent heat and specific heat capacity of foam concrete also increase. When the content of composite PCM is 30 %, the phase change temperature is 36.13 °C, the latent heat is 35.02 J/g, and the specific heat capacity is 2467 J/(kg·°C). The finite element simulation results show that when the PCFC with 30 % composite PCM is placed in the middle of the wall, the inside surface temperature fluctuation range of the PCFC-wall-2 is 27.293 °C ∼ 28.707 °C, and the temperature difference is 1.414 °C, which is 0.0738 °C and 0.047 °C lower than that of PCFC-wall-1 and PCFC-wall-3, respectively; the time for PCFC-wall-2 to reach the peak and valley temperature is delayed by 0.1667 h than the other two walls. The results indicate that using PCFC in buildings can reduce the energy required for building cooling or heating and affect energy saving and environmental protection. Moreover, PCFCs arranged in the middle of the wall has better heat storage and temperature regulation effect than those arranged on both sides.

A Study on Establishing Thermal Output Conditions of Radiant Ceiling Heating Panels for Improving Thermal Comfort of Perimeter Zone in Buildings

Amid concerns over airflow-induced transmission of the COVID-19 virus in buildings frequented by large numbers of people, such as offices, the necessity for radiant ceiling heating panels has increased. This is due to the concern that the airflows emitted from the convection heating systems installed near the ceiling or windows for winter heating may be a major cause of COVID-19 transmission. In this study, we aim to evaluate thermal comfort under various indoor and outdoor environmental conditions of a building and present the thermal output conditions of the radiant ceiling heating panel that can replace the convection heating system while ensuring comfort in the perimeter zone and handling the heating load. As a result, we were able to present, in a chart format, the thermal output conditions that can secure thermal comfort by analyzing the indoor airflow distribution depending on the surface temperature of the radiant ceiling heating panel, the interior surface temperature of the window, and the influence of internal heat generation. Moreover, through derived empirical formulas, we were able to determine the heating conditions of the panel that can secure the necessary heat dissipation while minimizing discomfort, such as downdrafts, even for indoor and outdoor conditions that were not evaluated in this study.

Experimental investigation on indoor thermal environment improvement and energy-saving of electrochromic window under Singapore's tropical climate

This study aims at analyzing the thermal performance improvement of a gray tintable electrochromic window (EC window) under Singapore's tropical climate. Two climate chambers were experimentally studied, one with a double-glazed EC window and another with a single-glazing window, the most common in the considered region, as the reference. The indoor thermal environment and air conditioning energy consumption were compared respectively to investigate the thermal performance improvement of the EC window. The results, under the sunny outdoor weather condition, showed that the EC window could achieve an interior surface temperature reduction of 4.4 °C under the tinted state and 3.0 °C under the clear state, compared to the reference window. Moreover, the bleached EC window achieved up to 37% improvement in peak Predicted Mean Vote (PMV) over the reference window, while the fully tinted EC window achieved a 50% improvement in peak PMV. Finally, the EC window under the fully tinted state could achieve up to 19% energy savings compared to the reference window. Using the EC window under Singapore's tropical climate can improve the occupant thermal comfort during the daytime and reduce air conditioning energy consumption.

Pre-cooling systems for hydrogen fueling stations: Techno-economic analysis for scaled enactment

Hydrogen fueling standards stipulates a sustainable cooling system technically and economically. Accordingly, the interior surface temperature of the on-board H2 storage tank in fuel cell electric vehicles must not exceed the maximum specified limit (358.15 K), and the fueling rate must be ≤ 42.86 sec / kg-H2, with T40 dispenser at 70 MPa. In this context, H2 refueling stations often employ double-tube and block heat exchangers for heat transfer. This study examines the H2 pre-cooling system for various loads and provides a comparative techno-economic analysis of double tube heat exchangers (DTHE) and microchannel heat exchangers (MCHE) under stipulated technical, operational, and outlet gas standards. For this purpose, thermal and hydraulic performances were simulated using ANSYS-CFX. Technical and cost models utilize manufacturer specifications and literature-based technical and economic characteristics to derive the minimum sustainable price, defined as the price to sustain the product. The results showed that the MCHE outperformed the DTHE for setups in mass manufacturing, improved effective heat transfer area, and predicted long term unit cost. The annual quantitative output affects manufacturing expenses and profit margins substantially. With high production rates, it is expected that the unit cost of the MCHE will decrease by up to 74%. In switching from DTHE to MCHE, general material requirements decreased by ∼60%, with scrap waste savings of ∼45% reflecting an appreciable footprint reduction.

Simulation and Optimization of Insulation Wall Corner Construction for Ultra-Low Energy Buildings

Approximately 40% of the overall energy consumption of society is consumed by buildings. Most building energy usage is due to poor envelope performance. In regions with cold winters, the corners of structures typically have the lowest interior surface temperature. In corners, condensation, frost, and mold are common. This has a substantial effect on building energy usage and residents’ comfort. In this study, the heat loss of corner envelopes is evaluated, and a suitable insulation construction of wall corners is constructed to increase the surface temperature of the envelope interior. Computational Fluid Dynamics simulation has been used to examine the heat transmission in a corner of an ultra-low energy building in this study. By comparing the indoor surface temperature to the soil temperature beneath the building, the insulation construction of wall corners has been tuned. The study results indicate that the planned insulation construction of wall corners can enhance the internal surface temperature in the corner and the soil temperature under the structure by approximately 8.5 °C, thereby decreasing the indoor–outdoor temperature differential and the heat transfer at ground level. In extremely cold places, the insulation horizontal extension belt installation can help prevent the earth beneath the building from freezing throughout the winter.

Thermal performance of indirect green façade in composite climate of India

Many experimental and theoretical studies have shown that green facades can increase the thermal efficiency of a building's façade. Previous field research has focused on humid subtropical and tropical climates and the Mediterranean climate. There has been no research directed at the Indian climates. Moreover, the studies have evaluated microclimate and inside surface or ambient temperatures; however, whether its application creates a comfortable environment is yet to be found. A real-time study was performed to assess the effect of indirect green facade systems on the glazed facade to evaluate thermal comfort in India's composite climate (Hot semi-arid climate Bsh). Two glazed facades were examined: one with a green screen of Bengal clock vine and the other bare to serve as the base case. The temperatures on the southwest-oriented green façades were up to 8.1°C lower than the respective temperatures of the uncovered façade. In summer, the nighttime temperatures for the vegetated façade were up to 5.1°C higher than those for the base facade. No significant insulating effect in the cold season was observed. The highest reduction was seen between 2 p.m. and 6 p.m., implying the relation with high solar radiation during these hours in the southwest orientation. While the green facade helped lower building temperatures, it also raised relative humidity, making an uncomfortable indoor thermal environment. The study also aimed to find the appropriate distance to install a green façade. Although a green façade controls temperature, the study finds that a proper distance between greenery and the facade surface improves the system's thermal performance. According to the study, installing a green facade with more than 150 mm distance between the greenery system and the façade surface is optimum in New Delhi's composite climate. The study's findings try to fill the gap of the impact of green facades in the Indian climate to see its applicability on a larger scale; however, the results show increased discomfort with higher relative humidity as the climate changes from dry to humid.